1. Field of the Invention
The present invention relates to an illuminating device used as a backlight in a liquid crystal display and a liquid crystal display incorporating such an illuminating device.
2. Description of the Related Art
In recent years, display devices using a liquid crystal panel, which is thinner than a CRT (cathode ray tube), have been widely used. The liquid crystal panel, not emitting light itself, displays an image by using external light or by being irradiated with light from an illuminating device.
Examples of illuminating devices for use in liquid crystal displays include the direct backlight proposed in JP-A-2004-191490 (pages 4 and 5, FIG. 2). This is used by being placed behind a liquid crystal panel, and has a light source formed of a substrate and LEDs (light emitting diodes) arranged all over the substrate, the liquid crystal panel being irradiated with light emitted from the LEDs.
In recent years, upsizing of liquid crystal display screens has been progressed, and concurrently therewith, larger substrates have come to be employed in direct backlights. Here, a large number of LEDs are mounted on a large substrate, which hinders the mounting of the LED, and the manufacturing yield is low, because the whole substrate needs to be replaced even when a failure occurs in a single LED on the substrate. In addition, the large substrate needs to be thick for the purpose of preventing bending occurring therein due to its own weight, and this prevents realizing thinner liquid crystal displays.
JP-A-2004-191490 proposes a backlight having a substrate on which LEDs are mounted in some sub units such that the brightness of the LEDs of each of the sub units is independently controlled. This, however, cannot help prevent the above problem, because a single substrate is used in the backlight.
Furthermore, the substrate having LEDs mounted thereon is provided at a bottom surface inside a housing, and hence the housing needs to be removed in order to take this substrate out of the liquid crystal display, and this increases the number of steps in the process.